sqlalchemy.exc.ProgrammingError for flask

Question

我有一个带有postgresql的flask应用程序，我想根据用户的好友名称对其进行排序。为了解释数据库，它在《老友记》中有一对一的关系，我使用了flask migrate和Alembic。但出现了这个错误，如果你能告诉我如何解决它，问题在哪里？

错误

sqlalchemy.exc.编程错误

ProgrammingError:（ProgrammingError）列"；users_1.name"；必须出现在GROUP BY子句中，或在聚合函数LINE 2:FROM用户加入（选择users.name作为名称，users_1.name作为

…^'选择users.id AS users_id，users.name AS users_name，users.age AS users_age、users.email AS users_email，users.bestfriend_id AS users_bestfriend-id\nFROM用户加入（选择users.name AS name，users_1.name AS fn\nFROM users JOIN users ASusers_1 ON users_1.id=users.bestfriend_id GROUP BY users.name）ASanon_1 ON anon_1.name=users.name ORDER BY anon_1.fn ASC\n LIMIT%（param_1）s偏移%（param_2）s'｛'param_1'：2，'param_2'：0｝

model.py:

friends = db.Table('friends',
db.Column('user_id', db.Integer, db.ForeignKey('users.id')),
db.Column('friend_id', db.Integer, db.ForeignKey('users.id'))
)
class Users(db.Model):
   id = db.Column(db.Integer, primary_key = True)
   name = db.Column(db.String(50), index=True)
   age= db.Column(db.Integer )
   email = db.Column(db.String(50),index=True, unique= True)
   bestfriend_id = db.Column(db.Integer, db.ForeignKey('users.id', ondelete ='SET NULL'), nullable=True)
   
   is_bestfriend = db.relationship( 'Users', uselist=False, remote_side=[id], post_update=True)

view.py

#condition to sort base on bestfriend name                  
    elif request.args.get('sort') == 'bf':
           sortBy = 'bf'
           friend = db.aliased(Users)
           sub = db.session.query(
                   Users.name, friend.name.label('fn')).
                   join(friend, Users.is_bestfriend).group_by(Users.name).subquery()
           monkey = Users.query.join(sub, sub.c.name == Users.name).
                        order_by(sub.c.fn.asc()).paginate(page, MONKEYS_PAGE, False)

Answer 1

您忘记通过将friend.name.label（'fn'）添加到组中

join(friend, Users.is_bestfriend).group_by(Users.name).group_by('fn').subquery()